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Then I realized I had flubbed the G-Code hack and had just run 6 cylinders at nominal current because I’d put the M907 in the wrong place, which explains why they all looked basically identical. So I fixed the G-Code, and redid the some of the tests. This time I ran the 2.0A before anything else to make sure I noticed a difference in the printer’s behavior and had gotten the current increase correct.

2.0A – Nothing ever extruded; the stepper shuddered and made an awful noise, but never actually completed more than a couple of steps. I’m guessing the motor is oversaturated at this point and simply can’t break from one magnetic field to the next.

1.5A – I’m kicking myself over this one. The test I had tried earlier in the day that made me think current couldn’t fix things, has definitely made a difference when I can get the code right. The best I’ve been able to get before is failing at the start of 7mm^3/s, but this took it over halfway into 9mm^3/s before failing (usually failing at 5mm^3/s).

I’m not convinced I heard a “skip” when the underextrusion happened though, but I didn’t see any grinding flats on the filament, and I haven’t tested the 1.25A-1.50A range, so this is at least progress. I will run more tests tomorrow or on Tuesday (as time allows) to test the range from nominal to 1.5A, then higher until I get grinding.

I am curious as to what this could mean in terms of the hardware. The mechanical engineer in me wants to say that this means I have a weaker feeder motor, which requires a higher current to get an equivalent torque as a nominal motor at nominal current. However, the mechanical engineer in me also reminds me I know bupkiss about electronic components and should consult those who do on the matter.

In the long term I think I’m uncomfortable running at 1.5A all the time, namely due to worry about excess current heat buildup in the PCB driving components and running components out of spec (this was mentioned somewhere in one of the many threads). Would this potentially be corrected (should further tests confirm this is the issue) by replacing the stepper motor, or could this be an issue with the PCB and the current that it supplies to the motor (eg a 1.5A command only gets 1.25A to the motor, etc)?

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DAS_Engineer - don't worry about harming the stepper or the electronics - they can both take it. Plus the other steppers (x,y,z) run at a higher current - I think 1.5A nominal setting.

The reason UM sets the current lower for the extruder is ONLY to avoid grinding filament.

I think in the above post, GEEKS is trying to say there are much more serious problems than this "current" issue and you should just try printing his or Ian's latest feeder.

Geeks, I like you and appreciate your contributions, but your posts translated to English are the most difficult to read of anyone. It would greatly help if you wrote very simple sentences with perfect grammar before translating. Write sentences meant for a 4 years old. Simple, short sentences. Each sentence should have a subject and a verb unlike my previous incomplete sentence.

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I meant: The stepper motor is stopped by the friction of the filament. Thereby increased its power leads to eating the filament on site.

No, you do not give me. And yes, I have an English so poor. But thanks to you and thanks to our perseverance, I can learn a few words. I often read your post completely before me traduction via Google. But it is true that this does not apply to intern full immertion.

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Hi gr5 - that's good to know, I didn't know if the stepper driver circuitry was different between the 4 steppers, or if it was 4 identical drivers merely being controlled differently.

I do agree that there are concerns with the feeder housing and internal friction; I'm actually trying to design my own with a completely "frictionless" path up until the bowden tube entry by making use of grooved roller bearings as entry and exit guides. I'll definitely share for review as soon as I get time to wrap it up and can source some 'reasonably' priced grooved bearings in the spec I'd need.

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Das - Try running tests over 1500 and see where it starts to strip the filament; that will provide some sort of crude basis comparing your setup with others, to determine whether your motor is getting the same current with the same settings.

As George noted, it shouldn't be a problem running with higher currents; on most 3D printers the current adjustment is no more sophisticated than manually turning a tiny potentiometer, and stopping turning when things start (or stop) working.

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Did you Guys tryed to print the extrusion test at 200% speed? (twice the speed you will reach 12mm3/s at 6mm3/s band)

please post your findings, should be interesting to observe if underextrusion occurs in same rate as 100% tests. If someone passes the test at 200% speed and fails the 100% speed test this could indicate bended filament problems, fricion problems, heat problems, etc

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I can't think why the test wouldn't behave identically at double the speed, or double the flow. I'm pretty sure that the physical speed that the head is moving in x-y is irrelevant to the problem. The extrusion system's behavior is independent of what the head is doing while it is extruding: the limiting factor should always be the volume per second.

Printing the 5mm³/s layer at twice the speed is functionally identical to printing the 10mm³/s layer. Printing the former at 200% flow puts the same stress on the extruder as printing the 10mm³/s second layer, just while extruding a wall that's twice as thick (which might add some additional resistance to the material flow path).

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Printing the 5mm³/s layer at twice the speed is functionally identical to printing the 10mm³/s layer. Printing the former at 200% flow puts the same stress on the extruder as printing the 10mm³/s second layer, just while extruding a wall that's twice as thick (which might add some additional resistance to the material flow path).

It puts the same stress but in less time which means less heat and less bended filament to deal.

I agree the tests seems a bit stupid unless somebody tell that could print at 10-12mm3/s (200%speed) and can´t go over 6 or 7mm3/s with 100%speed

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That's not the case. Tried it. For me it depends on the filament I use. With UM Orange, I can print up to 10mm^3/s at 100% and it fails at 6mm^3/s at 200%.

Didn't increase the current though.

Do you mean it failed on the 3mm³/s band (which is really 6mm³/s, when printing at 200%), or that it failed on the 6mm³/s band (which is really 12mm³/s)? The latter would be consistent with being able to successfully print 10mm³/s.

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Hello. My name is Scott and I am addicted to printing cylinders. I printed my first cylinder in February and have not been able to stop since then. I keep telling myself there are other things I need to print, but it is always a cylinder that ends up on my build plate. Printing cylinders used up all of the best filament I had. My wife thinks it is strange that I spend so much time watching cylinders print and that I save every one. She doesn't understand all of the notes I take about cylinders. Sometimes my wife gets angry with me because I spend more time printing cylinders than with her. I have lost sleep thinking about printing cylinders and have gotten out of bed before I should because I wanted to print a cylinder. All of my free time is spent printing cylinders. I have almost been late for work because I don't know when to stop printing cylinders.

I know that my cylinders get worse over time and the odds are stacked against me. I know the machine always wins. It is just so exciting when I print a cylinder that comes out a perfect 10. I sit and watch thinking "Go cylinder!! Go!!" On one side of my brain I know that the next cylinder will be worse, and the next, and next. The other side of my brain says "Just try one more. You might get 2 - 10s in a row. How awesome would it feel to get 3 - 10s in a row!! Jackpot!!" I can't get that side of my brain to shut up. It is just too loud.

I wish I had never heard about printing cylinders. I wish I never printed that first cylinder. Printing cylinders is ruining my life.

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Now for the sciency stuff. I am done printing cylinders - really. All of the blue PLA that came with my UM2 is gone so I don't think further testing will be valid unless I print a whole bunch of new cylinders. Here is what I have discovered: My printer is as predictable as a fart in a whirlwind.

I printed 12 cylinders yesterday with both the motherboard and the feeder motor covers removed. I set up the printer so that a personal fan could blow from below on to the motherboard. I used an IR thermometer to monitor the temp of the power supply and the feeder motor.

Over the course of 12 back to back prints the power supply went from 16C to 44. The stepper motor went from 16C to 36. Both were at their highest temp during the 8th print.

Here are the results of my cylinder prints in order of printing:

1 = 9 ring

2 = 9

3 = 8

4 = 7

5 = 7

This was a first for my machine - getting pretty good results over 5 back to back prints. These first 5 had the fan blowing on the motherboard. The fan was off for the remaining prints. I wanted to see if the quality would get worse without the fan.

6 = 6

7 = 7

8 = 8.5 - there was 1 small skip in the 8 ring then failure at 9

9 = 7.5

This is the first time ever my prints improved over time. However, print #8 is when the UM filament came off of the spool and was hanging freely as it entered the feeder. For print 7 the filament was still wrapped around the spool. Between print 9 and 10 I inserted the silver PLA from Makershed into the feeder, leaving the remaining UM blue PLA inside the bowden tube, and manually ran the silver until it entered the bowden tube. I printed #10 with both colors starting in the tube so UM blue turned into Makershed silver. I will remind you that in previous tests I never had the silver score any better than 3.5

10 = 8 - the UM blue ran out at the start of the 4 ring and then the silver began. 8 is a huge improvement for the Makershed silver on my machine.

11 = 6.5

12 = 7

Today I printed 7 cylinders in the Makershed silver. The first 3 were printed with the motherboard and feeder motor covers removed and no fan.

1 = 6

2 = 6.5

3 = 5.5

I then replaced both covers to see if the quality would get worse.

4 = 6

5 = 5.5

6 = 6

7 = 6

This is an amazing result for my machine - 7 prints of almost equal quality. I have no idea what has changed. It might be that I sent all of my bad vibes to Aaron's machine in Virginia, or maybe the moon is just right. The only other thing that changed was that I flipped over the power supply yesterday to have the solid black side up so I could get a better temp reading.

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I just realized that something has changed. After my last nozzle cleaning I had it screwed all the way into the silver cylinder. Illuminarti corrected me and I unscrewed it "some." I'm not sure how much, I used my "precision eye." I will have to borrow some feeler gauges and measure the distance between the silver cylinder with the perimeter holes and the teflon piece when this C-130 print ends later tonight.

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